Current methods of obturating (filling) an extirpated (stripped) root canal commonly involve packing a root canal with a thermoplastic material, such as gutta percha (e.g., trans 1-4 polyisoprene, Vectra™ or polysulfone), so that the root canal space is filled with the thermoplastic material. Preferably, the space is filled with the thermoplastic material forming a seal which prevents leakage between the root canal and the surrounding tissue.
It has been found that a satisfactory seal can be formed by softening the thermoplastic material by heating it prior to inserting it into the root canal. Normally, the gutta percha is applied to a carrier prior to insertion into the root canal in order to facilitate insertion. Carriers pre-coated with gutta percha are known, as shown by U.S. Pat. No. 4,758,156 issued on Jul. 19, 1988 to the inventor of the present invention and which is incorporated herein by reference. However, carriers pre-coated with gutta percha are expensive to purchase, and a less expensive means is desired for applying gutta percha to a carrier.
Although traditional thermoplastic compositions may be utilized in obturation carriers (e.g., Thermafil® Plus by Dentsply International, Inc, Soft-Core® by Axis Dental) that are generally effective in treating root canals, it would be desirable to have a carrier formed of a cross-linked composition. Thermoplastic materials, which are stable during high temperatures, must be crystalline and very hard. As such, a rotating file cannot penetrate the thermoplastic materials, and instead simply slides to one side of the carrier. This makes re-treating root canals somewhat difficult and certainly different than other obturation techniques like cold lateral and warm compaction.
By providing a carrier formed of a cross-linked material such as a thermoset material like rubber (e.g., gutta percha), retreatment of a root canal may be simplified. Ideally, the improved cross-linked carrier composition would have a desirable stiffness while generally being capable of maintaining its shape after the application of heat (e.g., during retreatment of a tooth). The present invention provides such improved carrier compositions having a cross-linked network and the desirable properties associated therewith.